Wood planing machine having means responsive to thickness variations in work pieces for automatically adjusting a cutterhead



Nov. 11, 1958 CARLSQN 2,859,780

wooo PLANING MACHINE HAVING MEANS RESPONSIVE TO THICKNESS VARIATIONS IN WORK PIECES FOR AUTOMATICALLY ADJUSTING A CUTTERHEAD Filed March 11, 1957 e Sheets-Sheet 1 TO ACCUMULAT Lewis B. CaflZ oza, 6953.0 M,7M #7 4 flags 2,859,780 SIVE Nov. 11, 1958 L. B. CARLSON wooo PLANING MACHINE HAVING MEANS RESPON TO THICKNESS VARIATIONS IN WORK PIECES FOR AUTOMATICALLY ADJUSTING A CUTTERHEAD 6 Sheets-Sheet 2 Filed March 11, 1957 1220832303 lew ls'fl. 0122 36022, y M aa-vgmmh r wwefl y NOV. 11, 1953 1 CARLSON 2,859,780

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AUTOMATICALLY ADJUSTING A CUTTERHEAD 6 Sheets-Sheet 4 Nov. 11, 1958 L. B. CARLSON WOOD PLANING MACHINE HAVING M EANS RESPONSIVE T0 THICKNESS VARIATIONS IN WORK PIECES FOR AUTOMATICALLY ADJUSTING A CUTTERHEAD 6 Sheets-Sheet 5 Filed March 11, 1957 2,859,780 NSIVEI 6 Sheets-Sheet 6 L. B. CARLSON WOOD PLANING MACHINE HAVING MEANS RESPO TO THICKNESS VARIATIONS IN WORK PIECES FOR AUTOMATICALLY ADJUSTING A CUTTERHEAD 1 o M w a a M W I r M 6 .IX u 0 I M B /////////J l L l/Ill V 0 M 4 W A :m I m u w m -1 -11 I 6 v 4 IJM 6* m 8 I Q u u H 1 w 8 U v 1 l 0 9% 1 \1 .L I p w u 8 WM U. m-.. ,0 -i 4 u M w o A fl W 8 U M Q. y 4 M I ///4Q m I fm n Nov. 11, 1958 Filed March 11, 1957 WOOD PLANING MAHINE HAVING MEANS RE- SPONSIVE TO THICKNESS VARIATIONS IN WORK PIECES FOR AUTOMATICALLY ADJ UST- ING A CUTTERHEAD Lewis B. Carlson, Milton, Mass., assignor to A. Woods Machine Company, Boston, Mass., a corporation of Massachusetts Application March 11, 1957, Serial No. 645,194

9 Claims. (Cl. 144-136) This invention relates to a planing machine for use on wood andthe object is to provide a' construction for such machine which, While preserving the high speed and large output of the better class of present-day machines, will consistently turn out finished work (surfaced stock) of high dimensional accuracy.

It is well known that boards, for example, are sold by a nominal thickness. Thus a one-inch board indicates aboard which at one time was about one inch or more thick. This referred to the rough board as cut from the log. A one-inch board surfaced on two sides is not an inch thick. It is usually considered to be about /8" which is approximately true if we permit a considerable tolerance. If we take a number of such boards and assemble them side by side, their surfaces will in general not be even, except for very rough uses.

We may consider what is known as match boarding, where the matter is further complicated by the location of the tongue and groove. It is common to cut a bead along one edge of the stock. This dissimulates by the projecting surface of the head a lack of registration at the joint. On the other hand, when we are laying a hardwood floor the surface is not level and after the boards are hailed down the entire surface of the floor is sanded down to proper smoothness. In various production uses a smooth surface may be so obtained, but of course, merely to grind away wood because that can be done is not a desirable practice, even if some sanding (with a lighter cut) may be desirable in further operations. The user who had no resource to large sanding machines, the worker on small and infrequent jobs and, in particular, the amateur (the do-it-yourself householder or the home workshop man) would find much use for more accurately dimensioned stock.

I am aware that various kinds of machinery have been automatically governed by controlling mechanism and in particular by feelers making contact with a template or with the work itself as delivered, or with parts left thereon or added thereto for control purposes. I do not know that any such control has been used or seriously proposed in connection with a wood planer of the present-day production type. In such a machine we have a series of boards differing among themselves, which are pushed along one by another in an endless stream along positioning guides along which they are advanced at high speeds and which are operated on by a series of percussive blows from knives moving in an entirely different path. Successive points of the finished surface are each determined by a single stroke of such a knife. There is no gradual removal of material to a predetermined limit. The mechanism involved is ponderous and the forces inducing vibration are rapidly recurrent and powerful. In an ordinary wood planer as now known the top head, for example, may be adjusted for a given depth of cut and clamped in position as efiiciently as may be. Theoretically we push a board through a limited passageway defined by a bed on one hand and the path of the knife edges on the ice other, and cut away what will not go through, and no more. In practice it is difficult to set up the head accurately and to return it to a like position after the various interruptions which occur in practice as, for instance, when the machine must be stopped to clear a jam. It has been observed, moreover, that in use the thickness of the work gradually increases, although the cutter blades are not so far worn down as to require resharpening, and although creeping of the supporting yoke has not been observed.

.Mill men attribute this to a slight change in the section of the blade edge in use, although the edge is still adequately sharp and makes an etficient cut. The effective diameter of the cutterhead (cutting circle) has decreased.

The machine which I am about to describe is designed to operate in practice with a tolerance of plus fifteen thousandths of an inch and minus zero in the thickness of the board produced permitting the mill operator to ofier to his customers boards varying in thickness by less than & of an inch. In particular when the increase in thickness above referred to has reached a predetermined limit a readjustment of that amount is automatically eifected to bring the actual cutting circle of the head (now diminished in diameter) to the same position relatively to the bed plate as the original cutting circle.

My invention will be well understood by reference to the following description of an illustrative embodiment thereof shown in the accompanying drawings.

Before proceeding to the brief description of the figures of the drawings it is pertinent to observe that since a wood planer is a large machine with many bulky parts which are of relatively complex contours and closely related in the assembled machine, it is practically impossible on the scale of a patent drawing to draw accurately and legibly assemblies showing all the parts. As manyparts, although embodying certain differences of structure to adapt them to the purposes of the invention, are in a sense conventional parts are freely omitted in the accompanying drawing, or their position merely indicated by an outline in order to disclose other features which would otherwise be hidden, and an exact matching up of figures which view'the machine from ditferent directions as would be possible with more complete figures is not always possible. 7

'Also'a wood planer in practice is built of sub-units. In the case of a top headas here shown the word stand is commonly used to denote a sub-frame, functionally immovable, which supports the chip-breaker and the cutterhead yoke in which the rotaryspindle of the cutterhead thought convenient to use the common names in describing the device of the drawing, and for clearness they have been carried over into the claims where they have no specific connotation but designate What might less simply have been called a supporting frame or sub-frame, and

a relatively movable cutterhead-carrying frame and so on.

In the drawings:

Fig. 1 is a transverse section through a planer taken in a plane just beyond the bottom head and the pressure bar and plate and looking toward the feeding in end of the machine. It might be considered as an end elevation of that part of the machine which is more particularly the subject matter of the following description;

Fig. 2 is a side-elevation of the structure shown in Fig.1 as seen from the right of Fig. 1, with parts broken away and in section;

Fig.3 is-a similar view differently broken and with parts omitted; t

Fig.4 is a section-on the line 4-4 of Fig. 1;

Fig. 5 is essentially a plan through the cutterhead stand and the cutterhead yoke with parts of the former broken away and in section and adjacent parts omitted;

Fig. 6 is a fragmentary section on line 66 of Fig. 5;

Fig. 7 is a plan of the pressure bar and pressure plate and adjacent parts which are just beyond the top cutterhead yoke, parts of which appear;

Fig. 8 is an elevation, with parts in section, of what is shown in Fig. l as seen from the lower side of that figure;

Fig. 9 is a fragmentary section on line 99 of Fig. 8;

Fig. 10 is a horizontal section on line 10--10 of Fig. 8 on a larger scale through a switch box and its supporting bracket, a cover being omitted at the upper side in the figure;

Fig. 11 is a section on line 1111 of Fig. 10;

Fig. 12 is a section on line 1212 of Fig. 11 but showing the cover; and

Fig. 13 is a wiring diagram of the circuits involved in the operation of the motor which raises and lowers the top cutterhead when it is operated automatically to correct the variance from the desired standard of thickness.

Referring now first to Fig. 2 of the drawings, the planer therein illustrated operates as do other machines of its general type on a series of rough boards, b, passed through the same in uninterrupted succession, one board pushing the other forward, the boards being fed by suitable feeding means, indicated herein by feeding rolls 10, over suitable supporting surfaces which cooperate with hold-down devices which maintain the boards pressed against the supporting surfaces, and this control of the boards is essential to the proper operation of the machine. Herein, as in other planers, the boards pass over a bed 12 beneath a so-called chipbreaker 14, yieldable to accommodate the various thicknesses of the rough boards and underneath the top cutterhead 16 which is carried by a cutterhead yoke 18 which is mounted, adjustably as will appear, on a cutterhead stand 20. In the wake of the bed 12 is the lower cutterhead 22 in its yoke 24, which removes stock from the bottom of the board. The board, reduced in thickness by the removal of stock from the top side passes from beneath the top cutterhead 16 under a pressure plate 26, the plane of the lower surface of which is nominally tangent to the cutting circle of the cutterhead 16. The pressure plate 26 is rigidly carried by a pressure bar 27 which is mounted on the top cutterhead yoke 18 with provision for vertical adjustment as will hereinafter appear. In normal operation the yoke and bar act as a unit with the two parts immovably connected. The bottom surface of the board, which is supported against upward movement by the pressure plate 26 is operated on by the knives of the bottom cutterhead 22 mounted in its yoke 24, and at the further side of the bottom head moves over the extension 28 of the bed suitably offset upwardly from the portion 12, which extension 28 is likewiseoverlaid by the pressure plate 26. Thus the finished board has a thickness corresponding to that between the pressure plate 26 and the extension 28 of the bed 12.

The major cut is made by the top head which reduces the quite variable thicknesses of the rough boards to a fairly definite thickness corresponding to the distance between the bed 12 and the overhanging right-hand end of the pressure plate 26, as seen in Fig. 2,. The cutting 'circle of'the lower head 22 projects somewhat above the plane of the bed 12 and takes a relatively light out of a constant amount, reducing the board to the finished dimension corresponding to the vertical distance between the surfaces 26 and 28. The board is guided on one side by a longitudinalguide or fence 30 (Fig. 1) toward which it is pressed in the usual manner. It may then proceed to further cutterheads performing suitable operations thereon, such as planing the edges, matching or profiling, such further mechanisms being not here shown since they are not material to an understanding of the principles of the invention.

The various parts are adjusted initially, or set up to provide the desired thickness of stock. When properly adjusted the board is reduced by the top head 16 to a thickness which will just pass under the pressure plate 26. If it were not so reduced there would be a jam. If it were much thinner the board would not be properly controlled for continued feed or for operation of the lower head. If properly set up its operation could theoretically be continued indefinitely, turning out perfectly dimensioned work, barring the usual interruptions from one cause or another. However, as already mentioned, as the knives dull the amount of stock removed by the top cutterhead varies and the thickness tends to increase. The experienced operator knows when the work starts to bind under the pressure plate and the difiiculty may be relieved by raising the pressure bar 27 and plate 26 slightly on the cutterhead yoke, as by means of the hand wheel 32 shown in Figs. 1, 7 and 8 operating suitable hoisting screws 34 mounted in yoke 18, the heads of which screws are seen in Fig. 7. It is unnecessary to show the details of these screws. This adjustment may be only a few thousandths of an inch. In the machine presently described such a manual adjustment is provided for. It is not attempted to make automatically a continuous correction for what amounts to a very gradual, essentially continuous, reduction of the cutting circle of the top head. However, when such manually effected adjustrnents have added up to a predetermined increase, say 12 or 15 thousandths of an inch, automatic means are provided for repositioning the parts by moving the cutterhead yoke downward for a compensating amount, so that its cutting circle, now of reduced diameter, is tangent to the same plane as originally. The pressure bar and plate moving with the yoke and having been moved upwardly to the reduced cutting circle, come down with it and the relation of the various parts, bed 12, pressure plate 26 and the cutting circle of head 16, is the same as in the original setup.

In planers as hitherto known, the top cutterhead has been vertically adjustable on its stand as is indeed required in order to permit a varied setup. It moved on suitable ways and when adjusted in the initial setup was clamped, generally by manually actuated clamps, in the adjusted position. In the present instance power means are provided for effecting this adjustment and suitable sensing means, such as a feeler cooperating with the stock in the plane of the bottom surface of the pressure plate is utilized for controlling the energization of the power mechanism, suitable constructions being provided for supporting the parts in such a way as to permit them to be quickly and accurately adjusted in the small amount required, while maintaining the rigid and accurate positioning of the parts in use.

Herein (see particularly Figs. 4 and 5 in correlation with Fig. 1) the cutterhead yoke 18 has extensions 36 embracing suitable ribs 37 on the cutterhead stand and is arranged to be moved vertically by screws 48 tapping therein and rotatively mounted in the overhanging portions 42 of the cutterhead stand. These screws (Fig. 4) are provided with worm gears 44 with which cooperate worms 46 on a cross shaft 48 driven by motor 50. This is a reversible motor which may be energized by a suitable manually operated three-way switch operated in either direction to raise or lower the cutterhead in the initial setup of the machine. In the automatic action it is utilized to lower the cutterhead yoke 18 and the pressure bar 27 and plate 26 carried thereby.

The cutterhead yoke in the automatic adjusting movement must move easily for a small amount and sto quickly. To facilitate the action it may be supported from beneath (see Fig. 1) by hydraulic pistons 52 in hydraulic cylinders 54, supportcd from, the side frames of the machine, which are supplied with hydraulic fluid from a suitable accumulator, not shown, arranged in wellknown manner to provide a constant upward pressure on the cutterhead yoke. The latter is backed up against the hydraulically exerted supporting pressure by the screws The requirements of the situation callalso for guiding of the yoke and its support in such a manner that it can move freely yet without play, and herein as best seen in Figs. 3, 5 and 6, the extensions 36 of the yoke 18 and the ribs 37- on the stand 20, which receive them have a length substantially greater than the diameter of the cutting cylinder and an exact fit is maintained by suitable gibs. The contacting surfaces are finished as accurately as feasible and may desirably be chromium plated to permit the movement with minimum friction. In Figs. 5 and 6,.the right-hand side of the former figure, we see the triangular gibs .60 and 62, the former of which may be adjusted vertically by screw 68 to draw the opposite surface 66 of yoke extension 36 to the opposite side of the machine (right of Fig. 5) against its bearing on rib 37 of stand 20 while the latter gib 62 is supported by the adjusting screws 70. As seen in Figs. 5 and 3 the extensions 36 of the cutterhead yokeare pressed longi tudinally (upwardly viewing Fig. 5) against the opposed surfaces of the ribs 37 by similar pairs of gibs 60a and 62a, controlled by similarly acting screws 68a and 7tla.

There will now be described the method of energizing the power means to reposition the parts when the dimension of the work has exceeded the predetermined tolerancc. In the present instance a feeler in the form of a roll 89 makes contact with the top of the board (b in Fig. 1). The normal position of the lowermost part of the roll is in the plane of the bottom of the pressure plate 26 because the pressure plate closely confines the board which is passing between it and in a sense the control operates responsively to the position of the lower surface of the pressure plate. For this reason and also because there is really no other suitable place to put it and have the pressure plate extend the desired distance to maintain control of the boards, it may project through a suitable hole in the pressure plate near guide 30 as seen in Fig. 8. It is normally positioned, as stated, so as to lie flush with the bottom of the pressure plate as it has to do if the board is passingacross the bottom, and this prevents it dropping lower in case of any interruption of the feed or of dropping into some defect of the board .at its end which might cause the succeeding board to foul.

As seen in Figs. 8 and 9 the roller 80 is mounted in a yoke 82 on the end of a rod 84 guided in box-like frame 86 mounted on the pressure bar 27 to move therewith. Herein the frame has a cross-headed rib 88 secured thereto fitting an undercut groove 90 in pressure bar 27. The reduced end of the rod passes through the top of the box and is secured by a screw 92 tapping into the upper end thereof to a horizontal portion of arm M (hereinafter to be more fully described) and setscrews 96 through this arm on either side cooperating with the top of the frame provide for adjusting the roller relatively to the frame and hence relatively to the surface of thepressure plate. A spring 98 encircles the end of rod 84 and is interposed between the top wall of the frame and nuts 1116 adjustable on the reduced end of the rod. The setscrews 96 act against this. spring. I

The movements of the sensing device are utilized to operate control switches for energizing the motor 50 at the proper time, which control switches for purposes of the immediately following paragraphs we may consider ,as being mountedin a stationary position, being housed in, a -switchbox, 102 carried by a bracket 104 projecting upwardly from as et the side frames of the machine. The arm 94 has 'a lat'erally"extending oliset portion the end of which projects into the interior of the switchbox' 102 where it underrides a lever 106 pivoted on pivot 108. (See Figs. 10, 11 and 12.)

The end of arm 94 makes contact with the end of a screw 110 adjustably mounted in the left-hand end of the lever 166 viewing Fig. 11. A spring 112 presses this screw downwardly and tends to swing the lever counterclockwise against stop screw 114 which checks the lever in the horizontal position shown. Presented to the upper and lower surfaces of the lever respectively are the operating plungers of switches 116 and 118.

In Fig. 11 the details of the switches are not shown, but merely the external outlines of the switch units. Suitable commercial snap switches operating on very slight movement are available and may be used. In Fig. 11 an adjustment for the position of the lower switch within the box is partially illustrated, but need not be described in detail.

The upper switch 116 normally tends to close except when it is supported in open position by the arm 106 in the horizontal position of the latter. A slight downward movement of the arm permits the switch to close. The switch 118 is normally open and is closed when the arm reaches its extreme downward position corresponding to the maximum variation in board thickness for which the machine is set up.

The electrical operation will be apparent from the diagram in Fig. 13. An energizing circuit for the motor 50 to cause it to operate in a direction to move the cutterhead yoke downwardly may be closed by bridge 120 operated by a solenoid motor 122. Two circuits to supply current to motor 122 are provided, one an energizing circuit controlled by switch 118 and the other a holding circuit partially controlled by the switch 116 but also by the bridge 124 which is closed by the solenoid motor when the bridge 120 in the motor circuit is closed.

When the stock is running with perfect thickness the arm 106 is horizontal and all the switches are open. As the board begins to get thicker and the arm starts to swing clockwise in Fig. 13 the switch 116 closes, but nothing happens because the circuit therethrough is open at 124. When the thickness of the board has reached the permissible maximum, arm 1116 closes switch 118 energizing the solenoid motor 122 and closing the bridge 120 for energizing the motor 50 and also the bridge 124. As soon as the motor 50 starts to lift the cutterhead yoke, arm 166 starts to move in the counterclockwise direction and switch 118 opens. However bridge 124 has closed the holding circuit and the solenoid motor 122 continues to be energized until the arm has reached the horizontal position corresponding to complete correction of the setting of the head and as it does so it opens switch 116, breaks the holding circuit, and switch 120 opens, stopping the motor St). Incident to such stopping of the motor a brake is applied thereto in well known manner.

As was stated above, in this operation the switchbox 102 with its switches are effectively stationary relative to the pressure bar and arm 94 carried thereby. Because the feeler 80 is accurately adjusted to the bottom surface of the pressure plate 26 and the pressure plate must at times, say when changing the setup of the machine or when clearing a jam or in other emergency, be moved for considerable distances, it is desirable to release the box 102 from this fixed position, enabling it to be moved, to one side as it were, with the pressure plate, yet returned with it to the former relative positions. For this purpose thebracket 104 supporting the box is provided with a dovetail 128 (see Fig. 10) fitting a corresponding dovetailed guideway 130 on the back of the box, which latter guideway includes a movable gib 132, A manually operated binder lever 134 (Fig. 8) supported by parallel links 136 from the pressure bar is operable to turn pressure screw 138 to clamp the gib against the dovetail 128 or to release the same" and when the lever is in the full line position seen in Fig. 8 the switchbox is in a fixed vertical position along the bracket. A second arm 140 extends from the pressure bar 27 into the box and its end engages strong centering springs I42, mounted on the upper and lower walls of the box. When the lever 134 is drawn to the right in Fig. 8, to the dotted line position the gib 132 is loosened, the box 102 is only loosely guided and is free to move up or down relatively to the frame of the machine. It is then carried by the arm 140. The springs 142 are of such strength relative to the weight of the box 102 that the box is in effect rigidly connected to the pressure bar 27 when the former is free, yet the pressure bar and the arm may move relatively to the box when the latter is clamped to permit arm 94 similarly to move to actuate lever 106 to operate the switches.

The box 102 is provided (Fig. 12) with a cover 144 having suitable openings through which arms 94 and 140 pass. The openings are such as to permit the necessary movement of the arms and felt packing 146 excludes dust.

I am aware that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and I therefore desire the present embodiment to be considered in all respects as illustrative and not restrictive, as is in fact clear in several matters from the description itself. Reference is to be had to the appended claims to indicate those principles of the invention exemplified by the particular embodiment described and which I desire to secure by Letters Patent.

I claim:

1. A wood planing machine of the type wherein work is fed past a rotary cutterhead automatically adjustable to maintain a fixed dimension in the planed piece comprising a cutterhead stand having ways extending transverse to the surface to be worked, a cutterhead yoke for supporting a rotary cutter, said yoke having guiding portions closely fitting to and movable along said ways, cooperating means for controlling the position of said portions comprising on the one hand hydraulic pressure means exerting a substantially constant force in one direction on said portions and on the other adjusting screws for translating them, power means for isochronously operating said screws, a sensing device responsive to the dimension of the work as it leaves the cutterhead and means governed thereby for energizing and deenergizing said power means to move the yoke to compensate for variations in the dimension.

2. A machine as set forth in claim 1 wherein the guiding portions and ways have a linear extent substantially greater than the diameter of the cutting circle of the head and are provided with adjustable gibs of similar length for closely maintaining the plane of movement of the head.

3. A wood planing machine of the type wherein work is fed past a rotary cutterhead automatically adjustable to maintain a fixed dimension in the planed piece comprising a cutterhead stand having ways extending transverse to the surface to be worked, a cutterhead yoke for supporting a rotary cutter, said yoke having guiding portions closely fitting to and movable along said ways, the guiding portions and ways having a linear extent substantially greater than the diameter of the cutting circle of the head and being provided with adjustable gibs of similar length for maintaining the plane of movement of the head, adjusting screws cooperating with said guiding portions for translating them, power means for isochronously operating said screws, a sensing device responsive to the dimension of the work as it leaves the cutterhead and means governed thereby for energizing and deenergizing said power means to move the yoke to compensate for variations in the dimension.

4. A wood planing machine of the type wherein work is fed past a rotary cutterhead automatically adjustable to maintain a fixed dimension in the planed piece com prising a cutterhead stand having ways extending transverse to the surface to be worked, a cutterhead yoke for supporting a rotary cutter, said yoke having guiding portions closely fitting to and movable along said ways, the guiding portions and ways having a linear extent substantially greater than the diameter of the cutting circle of the head and being provided with adjustable gibs of similar length for maintaining the plane of movement of the head, adjusting screws cooperating with said guiding portions for translating them, worm wheels on the screws, a shaft having worms cooperating with said wheels, a reversible electric motor for driving the shaft, a sensing device responsive to the dimension of the work as it leaves the cutterhead and means governed thereby for energizing the motor to turn in the appropriate direction and for deenergizing the same to move the yoke to compensate for variations of the dimension.

5. A wood planing machine of the type wherein work is fed past a rotary cutter head automatically adjustable to maintain a fixed dimension in the planed piece comprising a cutterhead stand having Ways extending transverse to the surface to be worked, a cutterhead yoke for supporting a rotary cutter, said yoke having guiding portions closely fitting to and movable along said ways,

power operated means for isochronously translating said guiding portions along the ways, a sensing device responsive to the dimension of the work as it leaves the cutterhead and means governed thereby for energizing said power means to move the yoke to compensate for variations of the dimension.

6. A wood planing machine comprising a bed over which the work travels, a cutterhead stand, a cutterhead yoke mounted thereon for controlled adjustments to dispose its cutterhead at desired positions relatively to the bed, a pressure plate to confine the work to the bed after the work passes the cutterhead, the pressure plate being mounted on the yoke toward and from the work with provision for adjustment of the pressure plate relatively to the yoke, power means for moving the yoke, and means responsive to the movements of the pressure plate relatively to the yoke effective when the movements away from the work total a predetermined amount to energize said power means to return the yoke and the pressure plate as a unit for an equal amount.

7. A wood planing machine comprising a bed over which the work travels, a cutterhead stand, a cutterhead yoke mounted thereon for controlled adjustments to dispose the cutterhead in a desired position relative to the yoke, a pressure plate to confine the work to the bed normally rigidly related to the yoke, power means for moving the yoke, means for controlling the power means mounted adjacent the pressure plate for optional movement therewith and sensing means positioned to correspond to the position of the surface of the pressure plate which faces the work and having an actuating portion cooperating with said energizing means when the latter is stationary.

8. A wood planing machine comprising a bed over which the work travels, a cutterhead stand, a cutterhead yoke mounted thereon for controlled adjustment to dispose the cutterhead in a desired position relative to the yoke, a pressure plate to confine the work to the bed normally rigidly related to the yoke, power means for moving the yoke, means for controlling the power means, a mounting adjacent the pressure plate for said control ling means arranged for sliding movement, a manually operated clamp for fixing the mounting against such movement, sensing means positioned to correspond to the position of the surface of the pressure plate which faces the work and having an actuating portion extending into cooperation with said controlling means to actuate the same when the mounting is stationary and a connection between the pressure plate and the mounting, yieldable when the mounting is stationary but moving the mounting with the pressure plate when the former is free.

9. A wood planing machine comprising a bed over which the work travels, a cutterhead stand, a cutterhead yoke mounted thereon for controlled adjustments to dispose the cutterhead in a desired position relative to the yoke, a pressure plate to confine the work to the bed normally rigidly related to the yoke, power means for moving the yoke, means for controlling the power means positioned adjacent the plate, a feeler, a carrier for the feeler extending through the plate, a support for the carrier on the pressure plate having provision for adjusting the carrier to dispose the feeler tangent to the plane of the surface of the pressure plate which faces the work and an actuating device on the carrier extending into cooperation with the power energizing means to actuate the same to compensate for variations in thickness of the work passing across said lower surface.

References Cited in the file of this patent UNITED STATES PATENTS 919,958 Ross Apr. 27, 1909 1,077,945 Solem Nov. 4, 1913 2,442,492 Hassler et al. June 1, 1948 2,724,492 Kolbe Nov. 22, 1955 2,725,084 Carlson Nov. 29, 1955 FOREIGN PATENTS 265,268 Switzerland Mar. 1, 1950 

